The outline of the general plan was to establish an aerial route through Central Africa with landing-places as near as possible a hundred miles apart, with the necessary number of petrol and oil refilling stations, repair depots, dwellings for pilots and mechanics, telegraphic or wireless com? munications between landing-places, transport roads^ and all the necessary paraphernalia for an aeroplane service, which is perhaps more extensive than the average layman imagines. G.H.Q., R.A.F. Cairo sent out parties and individuals to their allotted sections of the route on which they were to find the requisite number of landing-places, to mark them out, and to report on them. Each landingplace was to be not less than 800 yards each way, so as to enable a machine of any size to land comfortably with the wind in any direction. Now a piece of ground 800 yards square which is level, or can be made level without an enormous amount of labour, with a firm and well-drained surface, sufficiently dry all the year round, and easy of access, is by no means easily found in the equatorial region between Khartoum and Bulawayo. The work entailed in the construction of these landing-places varies, of course, enormously. In desert country almost natural aerodromes are occasionally found requiring very little preparation beyond putting in large white circles which may be seen from the air, and flags or small white patches to mark the boundaries. In bush country the trees and bushes are first cut down and burnt, stumps removed, ant-hills destroyed, and the whole surface finally levelled and made as firm as possible, since soft ground is very bad for landing. All large trees near the boundaries are also cut down.